While the usual or myxoid-type
neurothekeoma has been reasonably well established as being a
tumor of neural origin, the cellular
neurothekeoma remains in disputed histogenesis. We studied a series of 11 cellular
neurothekeomas using
paraffin immunoperoxidase staining with
microphthalmia transcription factor (Mitf), NKI/C3, and S-100. The majority of the
tumors in our series stained with NKI/C3 (9/11) and Mitf (9/11). All failed to
stain with S-100. Furthermore, we divided our series of cellular
neurothekeomas according to cytomorphology;
tumors demonstrating predominantly spindled morphology, predominantly epithelioid morphology, and mixed spindle and epithelioid morphology. The two
tumors that failed to
stain with NKI/C3 both demonstrated predominantly spindled morphology. One of the
tumors that failed to
stain with Mitf showed exclusive spindled morphology, while the other showed mixed morphology (spindle and epithelioid). Two of the
tumors, which stained strongly with Mitf, however, showed exclusive epithelioid morphology. This current study furthers the concept that cellular
neurothekeoma is a
tumor of neuroectodermal origin, and further suggests that it may express some component of melanocytic differentiation.